1. Field of Invention
This invention relates to methods and apparatus for liquid level sensing.
2. Related Art
Level sensing in a tank, such as a tank for storing, heating and/or metering water in a coffee brewing machine, may be important for several reasons, such as for advising a user that the tank needs to be refilled, for determining a volume present in the tank, and/or preventing operation of the machine without sufficient water being present in the tank. Level sensing in such applications may be done in different ways. In one approach, a conductive probe may be used to detect the presence of the water in the tank by determining whether the resistance of a circuit including the probe drops below an absolute threshold, e.g., below 3000 ohms indicating the presence of relatively low resistance water in the circuit.